Accuracy and precision

Accuracy and Precision

File:Accuracy and precision.svg

Illustration of accuracy and precision.

Accuracy and precision are two important concepts in the field of measurement and statistics. They are often used to describe the quality of a measurement system or the results of a measurement process.

Definitions

Accuracy

Accuracy refers to the closeness of a measured value to a standard or known value. In other words, it is the degree to which the result of a measurement conforms to the correct value or a standard. Accuracy is often expressed as a percentage, indicating how close the measurement is to the true value.

Precision

Precision, on the other hand, refers to the closeness of two or more measurements to each other. It is a measure of the repeatability or reproducibility of the measurement process. High precision means that repeated measurements under unchanged conditions show the same results.

Relationship between Accuracy and Precision

File:High precision Low accuracy.svg

High precision, low accuracy.

Accuracy and precision are independent of each other. A measurement system can be:

• High accuracy, low precision: Measurements are close to the true value but not to each other.
• Low accuracy, high precision: Measurements are close to each other but not to the true value.
• High accuracy, high precision: Measurements are both close to the true value and to each other.
• Low accuracy, low precision: Measurements are neither close to the true value nor to each other.

Importance in Measurement

In scientific research and engineering, both accuracy and precision are crucial for ensuring the reliability and validity of results. Accurate and precise measurements are essential for making informed decisions and for the advancement of knowledge.

Factors Affecting Accuracy and Precision

Several factors can affect the accuracy and precision of measurements, including:

• Instrument calibration
• Environmental conditions
• Operator skill
• Measurement technique

Related Pages

• Measurement uncertainty
• Error analysis
• Statistical significance
• Calibration

Gallery

• 
  Comparison of accuracy and precision.

Accuracy and Precision

• Accuracy (trueness and precision)
  Accuracy (trueness and precision)
• High accuracy, low precision
  High accuracy, low precision